Osram Opto Semiconductor leads at the moment of publication over all competitors in µmol/J efficiency with their Osram Oslon Square LED emitters mainly in the deep blue 450nm, hyper red 660nm and far red 730nm direct toned LED packages.
In the 660nm package at nominal drive current 350mA the efficiency goes as high as 3.91µmol/J what is nearly double from white leds. Never the less the high efficiency you can get with this type of LED packages, you also have to take the driving current into account – the higher the driving current, the lower the efficiency gets.
So as a LED grow light designer you have to make the trade-off between maximal micromole to power efficiency by using a much higher number of LED packages (which are fairly expensive) or finding the sweet spot where price to micromole is at its highest point of return on investment.